The present invention relates, in general, to electronics, and more particularly, to methods of forming semiconductor devices and structure.
In the past, the semiconductor industry utilized various methods and structures to form pulse width modulated (PWM) power supply controllers there were used in a power supply system to regulate an output voltage to a desired value. In some cases, the PWM controllers used an external component to set the value of some of the operating parameters of the PWM controller. For example, an external resistor may have been utilized to set an operating frequency of a master clock of the PWM controller. One problem with the prior PWM controllers was that switching of the inductors of the power supply system and switching of the power transistors that controlled current through the inductors often generated noise that coupled through parasitic components into the voltages or currents that were formed by the external components. The switching induced noise often resulted in the desired parameter having an incorrect value.
Accordingly, it is desirable to have a PWM controller that utilizes external components to more accurately set parameters of the PWM controller.
For simplicity and clarity of the illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor or a cathode or anode of a diode, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor. Although the devices are explained herein as certain N-channel or P-Channel devices, a person of ordinary skill in the art will appreciate that complementary devices are also possible in accordance with the present invention. It will be appreciated by those skilled in the art that the words during, while, and when as used herein are not exact terms that mean an action takes place instantly upon an initiating action but that there may be some small but reasonable delay, such as a propagation delay, between the reaction that is initiated by the initial action.